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Woodstock Elementary School Final Report

The Traffic Calming Program (TCP) began a traffic calming project in the Spring of 1996 to address traffic problems identified along SE 47th Avenue, between Steele and Woodstock, as part of the Woodstock Elementary School Safety Project.

The goal of the project was to enhance street safety for younger pedestrians, and livability for local residents, by reducing the 85th percentile speed of vehicles using SE 47th Avenue closer to the legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the best device for streets like SE 47th Avenue, which are classified as Local Service Streets, are not transit or primary fire response routes and have vehicle volumes between 400 and 1700 vehicles per day. Speed bumps have proven to be effective tools to reduce vehicle speed without impacting access. It is not an intended goal to reduce traffic volume on low-volume Local Service Streets.

SE 47th Avenue serves a single family residence neighborhood and is adjacent to Woodstock Park at its north end. Steele, to the north, and Woodstock, at SE 47th Avenue's south end, are both Neighborhood Collector streets. SE 47th Avenue is relatively flat and straight, with side walks on its west side and curbs on both sides. A portion of the daily traffic on SE 47th Avenue is believed to be cut-through traffic due to a commercial area on Woodstock.

Open House

All residents along SE 47th Avenue were invited to an open house September 19, 1997 to review and comment on the proposed speed bump installation. Twelve people attended the open house. Those who attended expressed approval for the proposed project. There is no petition or voting process for School Safety projects as they are a council mandated activity.

Performance

Five 14-foot speed bumps, at 275 to 400 foot spacing, were constructed along the 0.3 mile segment of SE 47th Avenue, Steele to Woodstock, on October 5, 1996 by the Bureau of Maintenance.

Vehicle Speeds

As the graph shows, vehicle speeds, previously concentrated between 23 and 25 mph, have been shifted into the range of 20 to 22 mph. The average 85th percentile vehicle speed before the project was 30.2 mph. Since bump construction the average 85th percentile speed is 22.9 mph and ranges from a low of 19 mph (near the bumps) to a high of 25 mph. Prior to installation of the speed bumps 35-57% of drivers exceeded the posted speed limit of 25 mph and 1-6% exceeded the limit by 10 mph or more. Since bump construction 1-12% of drivers exceed the posted speed limit and 0-0.9% exceed the limit by 10 mph or more.

Traffic Volume

Traffic volumes measured before bump construction averaged 750 vehicles per day (vpd) and varied from 600 to 900 vpd. After bump construction volumes average 530 vpd and range from 350 to 660 vpd. Simultaneously, traffic calming projects were in progress on SE 44th and SE 46th, streets parallel to SE 47th. Traffic volumes measured on SE 46th showed an increase since speed bumps were not yet constructed when the data for SE 47th was collected. SE 45th Avenue has also had a significant increase in traffic volume and will be closely monitored to determine if diversion has occurred.